The invention relates generally to keyboards for use in providing data input to computer systems, and relates particularly to keyboards generating pressure information permitting the computer system to warn the user if too much key pressure is being employed.
Much attention has been paid in recent years to carpal tunnel syndrome, tendonitis, and repetitive motion syndrome, terms used to describe the unhappy results often observed when one has been typing too much under poor conditions or with poor typing habits.
Approaches to this problem have included pads, chairs, desks, and supports intended to change the geometry of the hand-keyboard interaction. None has yet proven completely satisfactory.
It has been shown (Rempel et al., Fingertip Forces While Using Three Different Keyboards, Proceedings of the Human Factors Society 35th Annual Meeting, 1991) that with appropriate feedback, typists can alter the fingertip forces applied, and it has been speculated that this may reduce the abovementioned risks.
U.S. Pat. No. 4,795,888 to MacFarlane discusses changing the key pressure required to accomplish key closures by means of a variable pressure bladder. U.S. Pat. No. 4,918,560 to Storer discusses pairs of switches used in industrial settings where both switches must be actuated, thus protecting the hands from harm; the pressure required to operate the switches is selected so as to reduce the likelihood of carpal tunnel syndrome. U.S. Pat. No. 5,004,196 to Gross shows adjustable pad supports designed to minimize unsupported arm and wrist movements at a keyboard so as to reduce the likelihood of carpal tunnel syndrome.
U.S. Pat. No. 4,313,113 to Thornburg shows a keyboard with keys having individual pressure sensors. U.S. Pat. No. 4,647,916 to Boughton shows a keyboard with a variable pressure input. None of these references shows use of pressure information relating to carpal tunnel syndrome.
There is thus a need for a system that will provide feedback to the user of a keyboard or to co-workers of the user to permit the user to modify typing habits in favor of a key pressure consistently below a threshold chosen to minimize harm and to otherwise benefit the user.
A keyboard system is provided for use in data entry. The keyboard generates signals indicative of key closures, and also generates signals indicative of the pressure with which the user has pressed the keys. If the pressure exceeds a threshold, such as 200 grams, for a pressures averaged over a predetermined interval, such as three minutes, then this event is annunciated. In a single-user environment the annunciation is to the user. In a multi-user environment the annunciation is to a system manager.
Some investigators have suggested that appropriate limits on key pressure be 180 or 190 grams, or 300 grams, depending on the application and particular keyboard design.
In another embodiment of the invention, the system detects and annunciates the event of any single keystroke being made at a level higher than a predetermined threshold.
Alternatively, the system is set up to define distinct physical regions of the keyboard, and compiles key pressure information with respect to the regions. In the event that there has been too much pressure over a predetermined interval with respect to a region, that event is annunciated. The defined regions may, for example, be divided according to which hand is used or according to which finger is used. In keyboards having a separate numeric keypad, the system may compile information separately with respect to characters typed at the numeric keypad. The system may also be set up to compile key pressure information with respect to characteristics of characters being typed. For example, information may be compiled regarding all capital (upper-case) letters typed, or regarding all numerals typed. In all these cases under program control it is possible to annunciate events such as the use of excessive pressure, or to maintain statistics for use in evaluating the progress of a user in modifying his or her typing habits.
Optionally wrist support pads are also provided in front of the keyboard, each of which is equipped with a pressure sensor. The system monitors the wrist pad pressure readings to detect unfavorable combinations of wrist pad pressure and key depressions. The support pad may be shaped with a hole through which the operator places the hand, which is thus useful for teaching proper technique and assisting a user in avoiding injury.